#include <bits/stdc++.h>
using namespace std;

/*
ショトカ登録
cin cout endl return void
int double string char
pair make_pair first second tuple make_tuple get
sort erase swap map set insert
stoi reverse to_string
auto bool true false
vector queue priority_queue front pop_frpnt
size substr push_back pop_back push pop top
if for while break continue next_permutation
__builtin_popcount 
*/

//無限
int inf = 1020304050;
int64_t INF = 1020304050607080900;

//モッド
int64_t mod = 998244353;

//all マクロ
#define all(v) v.begin(), v.end()

//int64_t
typedef int64_t lint;



int main () {
    //少数以下
    cout << fixed << setprecision(15);

    lint N; cin >> N;
    string S; cin >> S;
    vector<lint> U(N, 0), D(N,0);
    for (lint i = 0; i < N; i++) {
        if (S[i] == '+') U[i]++;
        if (S[i] == '-') D[i]++;
    }
    for (lint i = N - 2; i >= 0; i--) U[i] += U[i + 1];
    for (lint i = 0; i < N - 1; i++) D[i + 1] += D[i];

    lint MAX = 0;
    for (lint i = -1; i < N; i++) {
        lint c = 0;
        if (i >= 0) c += D[i];
        if (i + 1 < N) c += U[i + 1];
        if ((i >= 0 && S[i] == '0') || (i + 1 < N && S[i + 1] == '0')) c++;
        MAX = max(MAX, c);
    }

    cout << MAX << endl;

    //for (auto x : U) cout << x << ' ';
    //*/
}